Download the source for the dependency
git clone https://github.com/ipa320/cob_perception_common.git
Dowload the source for this code
git clone https://github.com/ipa320/cob_people_perception.git
Add your path to your ~/.bashrc. For example, if you cloned the file into your home directory, you would add the following line to you ~/.bashrc. Make sure it's after the source declaration you made when you installed ROS:
export ROS_PACKAGE_PATH=$ROS_PACKAGE_PATH:$HOME/cob_perception_common .
At this point your going to have to update your ~/.bashrc either by closing your current terminal and opening a new one or using the command bash --login
Finally, go to the cob_people_detection directory with
roscd cob_people_detection
and build the package and all of its dependencies by typing
rosmake
Please see the wiki.